The present invention relates to an apparatus and method useful for disinfecting a contact lens. More particularly, this invention relates to such an apparatus and method in which the presence of, and preferably the substantial absence of, an oxidative disinfectant is indicated. Contact lenses should be periodically disinfected by the user to prevent infection or other deleterious effects on ocular health which may be associated with contact lens wear. Currently, there are several different conventional systems and methods which enable the user to disinfect his/her contact lenses between wearing times. These conventional cleaning and disinfection systems can be divided into "hot" and "cold" systems. Hot systems require the use of heat to disinfect the contact lenses, whereas cold systems use chemical disinfectants at ambient temperatures to disinfect the lenses.
Within the realm of cold disinfection systems are oxidative disinfectant, in particular hydrogen peroxide, disinfection systems. Disinfecting hydrogen peroxide solutions are effective to kill the bacteria and fungi which may contaminate contact lenses. However, residual hydrogen peroxide on a disinfected contact lens may cause irritation, burning or other trauma to the eye unless this hydrogen peroxide is destroyed, i.e., decomposed, neutralized, inactivated or chemically reduced. Therefore, destruction of the residual hydrogen peroxide in the liquid medium containing the disinfected contact lens is needed to enable safe and comfortable wear of the disinfected contact lens.
In order to avoid trauma to the eye caused by the presence of oxidative disinfectant on or in the lens, it would be advantageous to have an indication of the presence of such oxidative disinfectant. Additionally, it would be advantageous to have an indication of the substantial absence of such oxidative disinfectant, e.g., so that one would know it was safe to place the disinfected lens into one's eye.
Iodide ion is known to react with hydrogen peroxide to form free iodine which has a distinctive color. See, for example, Oakes U.S. Pat. No. 3,183,173. However, iodine has a substantial affinity for many contact lens materials so that the presence of free iodine in the liquid medium containing the oxidative disinfectant is to be avoided to prevent degradation of the contact lens.
There continues to be a need for a contact lens care system which effectively disinfects a contact lens and provides an indication of the presence of the oxidative disinfectant so that the disinfected lens can be safely and comfortably worn.